Prognostic Implications of MicoRNA miR-195 Expression in Human Tongue Squamous Cell Carcinoma

BACKGROUND miR-195 is aberrantly expressed in multiple types of disease. But little is known about the dysregulation of miR-195 in tongue squamous cell carcinoma (TSCC). In this study, we investigated the roles of miR-195 in the development and progression of TSCC. METHODS Using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), we evaluated miR-195 expression in TSCC samples from 81 patients. Overall survival of these patients was examined using Kaplan-Meier curves with log-rank tests and the Cox proportional hazards model. The expression of two known miR-195 target genes, Cyclin D1 and Bcl-2, was also examined in the TSCC samples by immunohistochemistry. The effects of miR-195 overexpression on cell cycle progression and apoptosis and its effects on the expression of Cyclin D1 and Bcl-2 were examined in transfected TSCC cell lines (SCC-15 and Cal27) using fluorescence-activated cell sorting assays, luciferase reporter assays, and Western blots. RESULTS Reduced miR-195 expression was associated with tumor size and the clinical stage of TSCC tumors. Kaplan-Meier survival analysis indicated that the TSCC patients with reduced expression of miR-195 had poor overall survival and in multivariable analyses low levels of miR-195 emerged as an independent prognostic factor for this clinical outcome. Levels of miR-195 expression were inversely correlated with the expression of Cyclin D1 and Bcl-2. Overexpression of miR-195 inhibited cell cycle progression, promoted apoptosis, and reduced Cyclin D1 and Bcl-2 expression in two TSCC cell lines. CONCLUSIONS miR-195 may have potential applications as a prognostic factor for TSCC patients.